Here we examine the large‐scale transport characteristics of the new “Middle Atmosphere” NASA Goddard Institute for Space Studies (GISS) climate model (E2.2). First, we evaluate the stratospheric transport circulation in historical atmosphere‐only simulations integrated with interactive trace gas and aerosol chemistry. Compared to lower vertical resolution model versions, E2.2 exhibits improved tropical ascent and older stratospheric mean ages that are more consistent with observed values. In the troposphere, poleward transport to the Arctic and interhemispheric mean ages in E2.2 are comparable to models participating in the Chemistry Climate Modeling Initiative. In addition to validating E2.2, we also assess its “transport sensitivity” using the coupled atmosphere‐ocean abrupt 4xCO₂ and transient 1%CO₂ simulations submitted to the Coupled Model Intercomparison Project, Phase 6, along with a 2xCO₂ simulation used to evaluate the linearity of the transport circulation's response to increased CO₂. We show that decreases (increases) in a stratospheric mean age (idealized surface loss) tracer scale linearly with increased lower stratospheric upwelling, which also increases linearly with warming tropical sea surface temperatures (SSTs). Abrupt 2xCO₂ and 4xCO₂ experiments constrained with (fixed) pre‐industrial SSTs are also used to quantify the relative importance of rapid adjustments versus SST feedbacks to the transport circulation responses in the model. Finally, sensitivity experiments are presented to illustrate the impact of changes in the convective parameterization on stratospheric transport.

中文翻译：

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GISS模型E2.2：针对中层大气优化的气候模型-2。大规模运输的验证和气候响应评估

在这里，我们研究了新的“中间大气层” NASA戈达德空间研究所（GISS）气候模型（E2.2）的大规模运输特征。首先，我们在仅历史大气的模拟中将平流层的运输循环进行了评估，并结合了交互式痕量气体和气溶胶化学。与较低的垂直分辨率模型版本相比，E2.2表现出更好的热带上升和更高的平流层平均年龄，与观测值更一致。在对流层中，E2.2向北极和半球平均年龄的极地转移与参加化学气候模拟倡议的模型相当。除了验证E2.2，我们还使用耦合的大气-海洋突变4xCO ₂和瞬态1％CO来评估其“运输敏感性”_2个用2xCO提交耦合模式项目，第6阶段，沿着模拟₂模拟用于将运输循环的响应的线性评估增加的CO ₂。我们发现，平流层平均年龄（理想化的表面损失）示踪剂尺度随着平流层下部上升流的增加呈线性下降（增加），而随着热带海面温度（SSTs）的增加也呈线性增加。突然2xCO ₂和4xCO ₂受（固定）工业前SST约束的实验还用于量化快速调整与SST反馈对模型中运输循环响应的相对重要性。最后，提出了敏感性实验，以说明对流参数化变化对平流层传输的影响。